Regeneration of the brush border of the proximal kidney tubule after isolateral ischemia has been monitored by transmission electron microscopy. The brush border takes longer to reform than does restoration of full activity of three enzymes (alkaline phosphatase, maltase, and gamma glutamyltranspeptidase) used as biochemical markers of brush border integrity. This project has been inactive this year but is still viable. We await the compilation of the biochemistry by LMA investigators.